Pneumatic cycle timer



Dec. 4, 1956 P. R. BROCK ET AL 2,772,688,;

PNEUMATIC CYCLE TIMER Filed Sept. 13, 1954 2 Sheets-Sheet l INVENTOREPETER R. BROCK WILLIAM F SCHMAUSS ALEXANDER v. d. LUFT BY 3 gw p HEIRATTORNEY Dec. 4, 1956 P. R. BROCK ET AL PNEUMATIC CYCLE TIMER 2Sheets-Sheet 2 Filed Sept. 13, 1954' GAGE PRESSURE 7'/ME(/N MINUTES)INVENTORS PETER RPBROCK WILLIAM F. SCHMAUSS T w w m L O d R m EeE D N TA X E L A United States Patent PNEUNIATIC CYCLE TIMER Peter R. Brock,Hagerstown, Md., and Alexander v. (l. Luft and William F. Schmauss,Martinsburg, W. Va., assignors to E. I. du Pont de Nemours & Company,Wilmington, Del., a corporation of Delaware Application September 13,1954, Serial No. 455,452

4 Claims. '(Cl. 137-102) This invention relates to an automatic cycletiming apparatus, and particularly to a widely adjustable, continuouslyoperable pneumatic cycle timer.

It is frequently necessary in industrial manufacturing to controlsimultaneously the performance of paired repetitive operations by theuse of cycle timers, the most common types of which are spring-actuatedor electrical clock devices. Spring-actuated apparatus requires periodicwinding, which is disadvantageous, and apparatus employing electricalenergy as the power source is objectionable from the standpoint of fireor explosion hazards.

An object of this invention is to provide a continuously operablepneumatic cycle timer for the coordination of at least one pair oftime-related repetitive operations which is widely adjustable to permitprecise time regulation of one operation of the pair with respect to theother, which is regulable over a relatively wide range of cycle timeintervals and which may be readily adjusted during operation.

Another object of this invention is to provide a cycle timer which iscompletely pneumatic and which is thus free from inherent fire andexplosion hazards.

Another object of this invention is to provide a pneumatic cycle timerwhich is simple in construction and maintenance, low in cost, reliablein operation and which is adapted to use in any manufacturing buildingprovided with air pressure service facilities.

The manner in which these and other objects of this invention areaccomplished will be apparent from the detailed description and thefollowing drawings, in which:

Fig. l is a representation of a preferred embodiment of timer accordingto this invention adapted to the control of a single pair of repetitiveoperations, all apparatus components except the interconnecting tubingbeing shown in section to facilitate understanding of the functioning ofeach, and

Fig. 2 is a time-pressure diagram comprising plots of the output signalcharacteristics of the apparatus of Fig. 1 (B and C) drawn to the samescale, but with origins displaced along the ordinate axis as indicated,together with a plot (A) of the pressure existing in chamber 108 ofreservoir 105, drawn to a different ordinate scale thanthe output signalplots and from yet a different origin, as indicated, but all three plotshaving a common time abscissa axis.

Referring to Fig. 1, air is supplied to the apparatus through lineconnected with the usual building air supply,- not shown, it beingassumed, of course, that a conventional pressure regulator is providedso that a substantially constant air pressure at the supply source isalways preserved, and at a suitable level for operaice nected to theinlet side of valve 17 of cycling relay 18, which is of the snap-actingtype.

Reverse-acting amplifying relay 11 may be a model 67-100R manufacturedby Moore Products Co., which comprises housing 22, provided with apressure-equalizing vent 23 opening to the atmosphere, within which ismounted the conventional double-bellows actuator, indicated generally at24, for the valving member of the device. Spring 25, biasing the valvingmember of 11 towards open position with respect to air flow through therelay from line 10, permits adjustment of the set point of the devicewithin a wide range of preselected values by regulating thumb screw 26supporting the end of the spring opposite the bellows.

The valving member of relay 11 comprises ball members 27 and 28 integralwith a common valve stem 29, the'upper end of the stem being integralwith a plate 30 fixedly attached to'the upper ends of the two bellows ofactuator 24 and thus constituting a bearing surface for spring 25. Plate30 is shown in section, as is the upper end of valve stem 29, to moreclearly show the exhaust opening from the interior of the inner bellowsof actuator 24 to the interior of housing 22 and thence to theatmosphere through vent 23, this passage comprising lateral ports 31 andaxial passage 32. With this'construc tion it will be understood thatvalve stem 29 rises and falls in a vertical plane as bellows actuator 24expands or contracts axially with, respectively, rise or fall inpressure applied to its annular interior.

Relay 11 is provided with a double valve seat 33, against the upper sideof which ball 27 abuts when the pressure within the interior of actuator24 is insufiicient to overcome the biasing action of spring 25, duringwhich time ball 28 is out of contact with the lower side of the seat.When the pressure within actuator 24 reaches a level such that spring 25is compressed, which is the condition in which the apparatus is shown inFig. 1, valve stem 29 moves upwardly, thus bringing ball 28 into tion ofthe control devices hereinafter described. Line contact with the lowerside of seat 33 and simultaneously lifting ball 27 from seated position.Valve stem 29 is provided with an integral cylindrical guide portion 34which fits within the central passage 35 of seat 33 with sufficientclearance so that the flow of air through the passage is notsubstantially impeded, and a connecting passage 36 is provided in thehousing body in open communication with passage 35. Signal line 37 isconnected to the other end of passage 36. As is customary in pneumaticrelay construction, the lower end of valve stem 29 is extended to form aguide portion which is co-axial with the open end of line 10 and of areduced diameter such thatit does not impede free passage of air pastit, and plug 38 is provided with upraised projections 39 which serve asretaining lugs for the lower end of valve-biasing spring 40 which abutsball 28 and thus insures positive valving action at all times. It mightbe mentioned that flow of air through relay 11 is regulated exclusivelyby the positions of balls 27 and 28 with respect to valve seat 33 andthat the construction of the apparatus is such that there is freeservice air -fiow from line 10 through the relay to line 37 wheneverball 28 is moved away from contact with the lower side of seat 33. Relay11 is further provided with a passage 44 opening into the annularinterspace of actuator 24 and connected with line 45, which ishereinafter described in detail.

Direct-acting amplifying relay 14 may be a model 67 manufactured by theMoore Products Co., which is similar in construction to relay 11 in thatit is provided with a housing 46, a housing vent 47, a double bellowsactuator 48, an actuator-biasing spring 49 and a spring tensionadjusting thumb screw 50. This relay is provided with a valving membercomprising ball 51 integral with valve stem 52 which is secured at theupper end to plate 53in the same mannerasdescribed for.relay.11and.isalso provided with inner bellows venting means consisting of lateralports 54 and axial passage 55. The valving arrangement for relay 14differs from that-of relay 1-1 in that a valve seat is provided 'forball -51 at"'b-oth extremes of travel of valve stem S2,'the upp,erseat56being integral with the base ofhousing 46 while-the lower seatconsist-sofa continuous ring '57 integral withcentrally drilled plug'58. The recess 59 in whichball 51 moves communicates with a passage .60in the housing base which, .in turn,- communicates with the other signalline 61 through which controlisto be exercised, all ashereinafterdescribed in detaili Thus, when bellows actuator 48 is expanded axiallyunderinterior pressure, which is the condition represented in Fig. fl,ball '51 clears valve seat 57, closing against valve seat:56, therebypermitting free flow of service air from line 13 through the relay tosignal line 61. Conversely, vwhenthe pressure in the interior ofactuator 43 decreases, permitting spring '49 to collapse the doublebellows, ball 51clears seat 56 and abuts seat 57, therebyrelievingthepressurefinline-61 by escape of air around the upper partofvalve stem 52 and thence 'to the atmosphere through ports .54, passage55 and vent 47. Relay 14 is provided with abiasing spring 62, insuringpositive valve action, and apassage 63 connecting with line .64, whichsupplies air to actuator 48.as hereinafter described.

Snap-acting relay 18 may be a model RO49A2 manufactured by theMinneapoiis Honeywell Co., which comprises housing 69 provided withapair of springebiased valves, of which one, i..e., 17, hasbeenfhereinabovementioned, while the ctheris indicated at 70.Threaded-valve stop plugs 71 provided with integral dependingskirtportions 72 engage with the tapped upper endszof theopeningsconstituting the valve chambers in .thehead of housing 69 andlimit the upper displacement of-the-valves in the chambers, whilethelower ends of the chambers are providedwith valve seats 73, for valve.17, and 174, for valve 71), against which the respective valves closeatthe lower extremes of travel. The'lower ends of the stems of valves 17and '79 abut the neoprene diaphragm 77, which is attached by mountingplates 78 to the underside of the head of housing 69 inair-tighttrelationship anddefines therewith chamber 79, which is in opencommunication with the sides of valve seats 73 and 74 opposite theassociated valves and also with passage 80 connected to line $1. Thelowermost'mounting plate 78 is provided with a flange 32 which carriesrocking lever 83 pivoted at 84, the two ends of the lever being providedwith screw deflectors 8:3 and 89 bearing at the ends againstdiaphragm 77on the side opposite that abutting the valve stems of 17 and 70.

The lower part of housing 69 is provided with a chamber 99 closed 01f bydiaphragm'91 to which iss'ecuredthe end of rod 92, red 92 being slidablysupported-for movement lengthwise of the housing on ways-93, only one ofwhich is shown, attached tothe base of the housing. The opposite end ofrod 92 is biased in opposition to diaphragm 91 by springfi-i, adjustablein compression by thumbscrew 95. Yoke 96 is fixedly secured to rod '92and is bifurcated at the lower end, so that the two legs rest on theoutside surfaces of ways 93 and retain rod 92 in position thereon. Theupper end of yoke 96 is attached to one end of. coiledspring 97,-theoppositeend of which is secured by a pivot connection, not detailed, totongue integral with lever 83. Spring 97 pivots lever 83 in acounterclockwise direction, thuspermitting valve 17 to close under theaction of its biasing spring, when rod 92 is deflected to right-hand.position by the highest pressure, applied through diaphragm91,'attained in chamber 1% of reservoir .165, hereinafter described, andpivots lever 33 in a clockwise direction, thereby opening valve 17 andpermitting valve ;7-(i1to-close, under the lowest pressureattained-inchamber 108. Housing 69 is provided withia vent 99, connecting thechamber of valve 70 to atmosphere, and a passage 100 connected 4 to line.101, .which in .turn .is in open communication with passage 106 ofreservoir 195 and with line 45.

Reservoir comprises an air-tight vessel provided with an entrancechamber 107 and a pressure build-up chamber 108, the two chambers beingconnected through a throttling valve 109, thesetting of which isadjustable by thumbscrew 11010 .obtain a .widerange of preselected ratesof air flow through the valve. Airis supplied to the reservoir via line.81 .hereinbefore described, which is connected to inlet passage 5111.of entrance chamber 107.

Referring to Fig. '2, the operation of the embodiment described is bestunderstood by consideration of the pressure-time relationships existing,as regards chamber 108 of reservoir 195, and the correspondingrelationships resulting therefrom as regards-signal lines 37 and 61.

It should be pointed out that the pressure-time relationships depictedin Fig. 2 are represented with reference to a common time axis asabscissa but, to avoid confusing overlying of the pressure plots,eachhas been referred to a separate origin on the ordinate scale, thepressure scales for each of the two signal line pressures being of equalmagnitude, whereas the pressure scale for chamber 108 is magnified, .allin the interests of facilitating an understanding of operation.

-With atmospheric pressure existing in line 10, valve 17 of relay 18will initially be open and valve 70 will be closed, responsive to itsbiasing spring, whereas ball member 280f reverse-acting relay '11 willbe clear of valve seat 33 thereby permitting instantaneous full linepressure build up in signal line 37, as represented by plot C.Accordingly, relay 11 will be in on position, with ball member 27 closedagainst valve seat 33 under the influence of spring 25.

At the same time, ball member 51 of direct-acting relay .14 is closed onvalve seat 57 under the action of spring 49, thereby preventing passageof air through relay 1 4 to signal line 61, as indicated by plot B, andrelay 14 will be in off position considered with reference to the cyclethis relay controls. As superatmospheric pressure is applied to line 10,the pressure in chamber 198 will build up substantially linearly, asindicated'in plot Aof Fig. 2, by passage of air past open valve 17,through chamber 79, passage 80, line 81, passage 111, chamber 107, andthrottling valve 109, the rate of pressure build up being determined bythe setting of the latter valve.

Since chamber 108 is in open communication with bellows actuators 24 and48 through lines 101, 45 and branch line 64, these actuators are .biasedagainst their associated springs and, when the set point pressures ofeach are in turn attained, the actuators reverse the positions of theassociated valving members and reverse the conditions of the relays fromthose originally existing. Thus, as seen inplot A relay 14-remains inoff condition until the pressure in chamber 108 attains level d, whenrelay 14 opens and permits the pressureinline 61 (refer plot B) torisepractically instantaneouslyfrom atmospheric level to the full line,pressure carried in supply line 10.

As *the pressure'in chamber 108 continues to increase, the set pointpressure level of relay 11 is finally attained at point e, plot A,whereupon bellows actuator 24 closes ball member2'8 onseat 33, at thesame time lifting ball member 27 to open position, thus permittingexhausting from line 37 back through passages 36 and 35, the innerbellows of the actuator and thence to the atmosphere through ports 31,passage 32 and vent 23. Relay '11 thus reverts to'off condition asindicated by the first downward step of plot C.

The pressure in chamber 108 continues rising to the level x of plot Awhen diaphragm 91, responding to the pressure built up in chamber 90,pushes rod 92 to the right and thus triggers spring 97 to snap lever 83in a counter-clockwise directionpermitting valve 17 to close and openingvalve 7d. Fig. 1;represents .theapparatus at this instant of operation.Back flow is thereby permitted from chamber 108 and bellows actuators 24and 48 past needle valve 109 and through chamber 107, line 81, andchamber 79 with discharge to the atmosphere through vent 99. At point ofplot A the set point of relay 11 is again attained and this relay shiftsto on position again with the pressure in signal line 37 at once rising,as indicated in plot C. With further pressure drop in chamber 108 andbellows actuator 48 to point g of plot A, relay 14 reverts to offposition, as indicated in plot B. Finally, the pressure in chamber 108reaches level y, at which point snap-acting relay 18 functions under thebiasing force of spring 94 to shift rod 92 to the left, thereby causinglever 83 to tilt in a clockwise sense, closing valve 70 and openingvalve 17. The cycle hereinabove described then repeats continuously withvariation of pressure according to the sawtooth pattern of plot A aslong as operating air is supplied to the apparatus through line 10.

It will be apparent that the cycle times for each of the amplifyingrelays and also for the snap-acting relay are independently adjustableover very wide ranges. It will be understood that the signal lines areprovided with conventional pneumatic devices, known to those skilled inthe art, which are responsive to the pressures carried in these linesand thereby controlled by the apparatus of this invention. While onlyone pair of signal lines has been described, it is clear that more thanone such line may be connected to one or both of the two relays tosynchronize a multiplicity of operations or, of course, several pairs ofrelays may be employed with one reservoir to preserve independentcontrol for each pair of signal lines involved, provided that the timecharacteristic for the reservoir meets the requirements of the situationwhich it is desired to control.

The embodiment hereinabove described in detail makes possible theachievement of certain especially desirable operating conditions as.regards the downstream control instruments in circuit with the signallines and therefore the construction described is preferred. However, itwill be particularly understood that the pneumatic relays need not beemployed in directand reverse-acting pairs but that, instead, pairs, orgreater groupings, of either directacting or reverse-acting relays canbe utilized. With paired relays of the same types overlapping operationof each relay with respect to its paired relay is still attainable insimilar manner to that represented in Fig. 2, except that both relayswill then arrive at the same condition in each phase of pressurevariation in the reservoir, as distinguished from opposite phaseoperation for the preferred embodiment. Thus, with direct-acting relayspaired, both will go on with pressure rise in chamber 108, and off withpressure drop therein, while paired V reverse-acting relays functionoppositely, going on with fall in pressure and off with rise inpressure. It will be further understood that yet other relays may beutilized in series or in series-parallel relationship with the maincontrol relays hereinabove described to obtain a variety of desirablecontrol patterns suited to the requirements of the process or operationwhich it is desired to control, but such modifications are not describedin further detail as they do not relate to this invention.

From the foregoing it will be understood that this invention is capableof relatively wide modification by those skilled in the art withoutdeparture from its essential sprit, wherefor it is intended to belimited only by the scope of the following claims:

What is claimed is:

1. A pneumatic cycle timer comprising in combination a gas pressuresource, at least one pair of pneumatic relays each having service gasinlets in communication with said gas pressure source and service gasoutlets each in communication with at least one individual signal line,a cycling relay having a chamber provided with a valved port incommunication with said gas pressure source and a second valved portventing to atmosphere, said cycling relay being further provided withgas pressureactuated means for opening and closing said valved ports inalternation upon the application of preselected pressures to saidpressure-actuated means, a gas storage reservoir provided with two gasstorage chambers, a. throttling valve connecting said two gas storagechambers, gas passage means connecting said chamber in said cyclingrelay with one of said gas storage chambers, and other gas passage meansconnecting the other of said gas storage chambers in operativerelationship with said pressure-actuated means and with the actuatingmeans of said pneumatic relays.

2. A pneumatic cycle timer according to claim 1 wherein said pneumaticrelays are of the double bellowsactuated type.

3. A pneumatic cycle timer according to claim 1 wherein said throttlingvalve comprises a needle valve.

4. A pneumatic cycle timer comprising in combination a gas pressuresource, at least one direct-acting pneumatic relay and at least onereverse-acting pneumatic relay having service gas inlets incommunication with said gas pressure source and service gas outlets eachin communication with at least one individual signal line, a cyclingrelay having a chamber provided with a valved port in communication withsaid gas pressure source and a second valved port venting to atmosphere,said cycling relay being further provided with gas pressure-actuatedmeans for opening and closing said valved ports in alternation upon theapplication of preselected pressures to said pressure-actuated means, agas storage reservoir provided with two gas storage chambers, athrottling valve connecting said two gas storage chambers, gas passagemeans connecting said chamber in said cycling relay with one of said gasstorage chambers, and other gas passage means connecting the other ofsaid gas storage chambers in operative relationship with saidpressureactuated means and with the actuating means of saiddirect-acting and reverse-acting pneumatic relays.

Merwin July 31, 1951 Eckman Mar. 11, 1952

